What is CVE-2026-39861?

CVE-2026-39861 is a critical-severity vulnerability in Anthropic Claude_code, classified under Path Traversal. CVSS score: 10.0/10. Published 2026-04-21.

How severe is CVE-2026-39861?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Path Traversal in Anthropic Claude_code

CVE-2026-39861

Claude Code is an agentic coding tool. Prior to version 2.1.64, Claude Code's sandbox did not prevent sandboxed processes from creating symlinks pointing to locations outside the workspace. When Claude Code subsequently wrote to a path wit…

Vulnerability class: Path Traversal (Directory Traversal)

EPSS: 0.005 (40.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

Affected products

Anthropic Claude_code
Anthropics Claude-code — versions < 2.1.64

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2026-39861?: CVE-2026-39861 is a critical-severity vulnerability in Anthropic Claude_code, classified under Path Traversal. CVSS score: 10.0/10. Published 2026-04-21.
How severe is CVE-2026-39861?: Critical severity. CVSS v3 base score is 10.0 out of 10.